Screencast: flexfuel with racerom

[jamesm]

[ame="http://youtu.be/rD3zZ_tQHQg"]http://youtu.be/rD3zZ_tQHQg[/ame]

[u/Josh]

These videos are great.

One kind of off topic question though, why can/do you target a leaner (equivalent) AFR with E85?

[jamesm]

Originally Posted by u/Josh

These videos are great.

One kind of off topic question though, why can/do you target a leaner (equivalent) AFR with E85?

because it has a much wider operational range than gasoline, and burns much cooler due to the evaporative cooling properties of the ethanol. overall it's a much more forgiving fuel.

in lambda:

gas: rich best torque is 0.85, lean best torque is 0.9
e85: rich best torque is 0.714, lean best torque is 0.867

i typically shoot for around 11.6-11.8:1 on e85 for a boosted application, where i'd normally target 10.8-11.2:1 on 93. others go even leaner. i tend to be very conservative with my tunes. those last couple hp aren't worth tuning into knock and/or leaner than i'm comfortable with, to me at least. of course with e85 there is little to no risk of knock under load, but still better safe than sorry

[u/Josh]

That makes sense to me under heavy load, but at cruising load where knock isn't an issue and the gas tune is already quite lean, is it safe to lean it out still another point on E85?

[jamesm]

I messed up in the video, there's a load threshold on the map to keep it from effecting open loop or lower loads. Gotta edit that . You could definitely run gas equivalent 15.7:1 in cruise no problem won e85 though, from what I've read. Never tried it myself.

Alternatively use could use load on one axis of the custom map to vary it that way.

[SmsAlSuwaidi]

why use coolant temp ( complete tuning noob )

[jamesm]

Originally Posted by SmsAlSuwaidi

why use coolant temp ( complete tuning noob )

No good reason. Just an example. In the video I also suggest using rpm or load. Also manifold pressure is a good option, whatever you find useful to solve any problem you may be needing to solve. That's the power of racerom. You can literally do it any way you like almost without limitation.

In many cases the second axis isnt used for anything, like on the case of the fuel volume comp in this map. With further tuning we'd change it to be whatever we find necessary, when a problem arises that needs solving

[Sportsguy83]

The tune being used is so much full of WIN!